path: root/mutt_sasl.c

/*
 * Copyright (C) 2000 Brendan Cully <brendan@kublai.com>
 * 
 *     This program is free software; you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation; either version 2 of the License, or
 *     (at your option) any later version.
 * 
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 * 
 *     You should have received a copy of the GNU General Public License
 *     along with this program; if not, write to the Free Software
 *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 */ 

/* common SASL helper routines */

#include "mutt.h"
#include "account.h"
#include "mutt_sasl.h"
#ifdef USE_SSL
# include "mutt_ssl.h"
#endif
#include "mutt_socket.h"

#include <sasl.h>
#include <netinet/in.h>
#include <netdb.h>

/* arbitrary. SASL will probably use a smaller buffer anyway. OTOH it's
 * been a while since I've had access to an SASL server which negotiated
 * a protection buffer. */ 
#define M_SASL_MAXBUF 65536

static sasl_callback_t mutt_sasl_callbacks[5];

/* callbacks */
static int mutt_sasl_cb_log (void* context, int priority, const char* message);
static int mutt_sasl_cb_authname (void* context, int id, const char** result,
  unsigned int* len);
static int mutt_sasl_cb_pass (sasl_conn_t* conn, void* context, int id,
  sasl_secret_t** psecret);

/* socket wrappers for a SASL security layer */
static int mutt_sasl_conn_open (CONNECTION* conn);
static int mutt_sasl_conn_close (CONNECTION* conn);
static int mutt_sasl_conn_read (CONNECTION* conn);
static int mutt_sasl_conn_write (CONNECTION* conn, const char* buf,
  size_t count);

/* mutt_sasl_start: called before doing a SASL exchange - initialises library
 *   (if neccessary). */
int mutt_sasl_start (void)
{
  static unsigned char sasl_init = 0;

  sasl_callback_t* callback, callbacks[2];
  int rc;

  if (!sasl_init) {
    /* set up default logging callback */
    callback = callbacks;

    callback->id = SASL_CB_LOG;
    callback->proc = mutt_sasl_cb_log;
    callback->context = NULL;
    callback++;

    callback->id = SASL_CB_LIST_END;
    callback->proc = NULL;
    callback->context = NULL;

    rc = sasl_client_init (callbacks);

    if (rc != SASL_OK)
    {
      dprint (1, (debugfile, "mutt_sasl_start: libsasl initialisation failed.\n"));
      return SASL_FAIL;
    }

    sasl_init = 1;
  }

  return SASL_OK;
}

/* mutt_sasl_client_new: wrapper for sasl_client_new which also sets various
 * security properties. If this turns out to be fine for POP too we can
 * probably stop exporting mutt_sasl_get_callbacks(). */
int mutt_sasl_client_new (CONNECTION* conn, sasl_conn_t** saslconn)
{
  sasl_security_properties_t secprops;
  sasl_external_properties_t extprops;
  const char* service;
  int rc;

  switch (conn->account.type)
  {
    case M_ACCT_TYPE_IMAP:
      service = "imap";
      break;
    case M_ACCT_TYPE_POP:
      service = "pop";
      break;
    default:
      dprint (1, (debugfile, "mutt_sasl_client_new: account type unset\n"));
      return -1;
  }
  
  rc = sasl_client_new (service, conn->account.host,
    mutt_sasl_get_callbacks (&conn->account), SASL_SECURITY_LAYER, saslconn);
  
  if (rc != SASL_OK)
  {
    dprint (1, (debugfile,
      "mutt_sasl_client_new: Error allocating SASL connection\n"));
    return -1;
  }

  /*** set sasl IP properties, necessary for use with krb4 ***/
  /* Do we need to fail if this fails? I would assume having these unset
   * would just disable KRB4. Who wrote this code? I'm not sure how this
   * interacts with the NSS code either, since that mucks with the fd. */
  {
    struct sockaddr_in local, remote;
    socklen_t size;

    size = sizeof (local);
    if (getsockname (conn->fd, &local, &size))
      return -1;

    size = sizeof(remote);
    if (getpeername(conn->fd, &remote, &size))
      return -1;

#ifdef SASL_IP_LOCAL
    if (sasl_setprop(*saslconn, SASL_IP_LOCAL, &local) != SASL_OK)
    {
      dprint (1, (debugfile,
	"mutt_sasl_client_new: Error setting local IP address\n"));
      return -1;
    }
#endif

#ifdef SASL_IP_REMOTE
    if (sasl_setprop(*saslconn, SASL_IP_REMOTE, &remote) != SASL_OK)
    {
      dprint (1, (debugfile,
	"mutt_sasl_client_new: Error setting remote IP address\n"));
      return -1;
    }
#endif
  }

  /* set security properties. We use NOPLAINTEXT globally, since we can
   * just fall back to LOGIN in the IMAP case anyway. If that doesn't
   * work for POP, we can make it a flag or move this code into
   * imap/auth_sasl.c */
  memset (&secprops, 0, sizeof (secprops));
  secprops.max_ssf = (sasl_ssf_t) -1;
  secprops.maxbufsize = M_SASL_MAXBUF;
  secprops.security_flags |= SASL_SEC_NOPLAINTEXT;
  if (sasl_setprop (*saslconn, SASL_SEC_PROPS, &secprops) != SASL_OK)
  {
    dprint (1, (debugfile,
      "mutt_sasl_client_new: Error setting security properties\n"));
    return -1;
  }

  /* we currently don't have an SSF finder for NSS (I don't know the API).
   * If someone does it'd probably be trivial to write mutt_nss_get_ssf().
   * I have a feeling more SSL code could be shared between those two files,
   * but I haven't looked into it yet, since I still don't know the APIs. */
#if defined(USE_SSL) && !defined(USE_NSS)
  if (conn->account.flags & M_ACCT_SSL)
  {
    memset (&extprops, 0, sizeof (extprops));
    extprops.ssf = mutt_ssl_get_ssf (conn);
    dprint (2, (debugfile, "External SSF: %d\n", extprops.ssf));
    if (sasl_setprop (*saslconn, SASL_SSF_EXTERNAL, &extprops) != SASL_OK)
    {
      dprint (1, (debugfile, "mutt_sasl_client_new: Error setting external properties\n"));
      return -1;
    }
  }
#endif

  return 0;
}

sasl_callback_t* mutt_sasl_get_callbacks (ACCOUNT* account)
{
  sasl_callback_t* callback;

  callback = mutt_sasl_callbacks;

  callback->id = SASL_CB_AUTHNAME;
  callback->proc = mutt_sasl_cb_authname;
  callback->context = account;
  callback++;

  callback->id = SASL_CB_USER;
  callback->proc = mutt_sasl_cb_authname;
  callback->context = account;
  callback++;

  callback->id = SASL_CB_PASS;
  callback->proc = mutt_sasl_cb_pass;
  callback->context = account;
  callback++;

  callback->id = SASL_CB_GETREALM;
  callback->proc = NULL;
  callback->context = NULL;
  callback++;

  callback->id = SASL_CB_LIST_END;
  callback->proc = NULL;
  callback->context = NULL;

  return mutt_sasl_callbacks;
}

int mutt_sasl_interact (sasl_interact_t* interaction)
{
  char prompt[SHORT_STRING];
  char resp[SHORT_STRING];

  while (interaction->id != SASL_CB_LIST_END)
  {
    dprint (2, (debugfile, "mutt_sasl_interact: filling in SASL interaction %ld.\n", interaction->id));

    snprintf (prompt, sizeof (prompt), "%s: ", interaction->prompt);
    resp[0] = '\0';
    if (mutt_get_field (prompt, resp, sizeof (resp), 0))
      return SASL_FAIL;

    interaction->len = mutt_strlen (resp)+1;
    interaction->result = safe_malloc (interaction->len);
    memcpy (interaction->result, resp, interaction->len);

    interaction++;
  }

  return SASL_OK;
}

/* SASL can stack a protection layer on top of an existing connection.
 * To handle this, we store a saslconn_t in conn->sockdata, and write
 * wrappers which en/decode the read/write stream, then replace sockdata
 * with an embedded copy of the old sockdata and call the underlying
 * functions (which we've also preserved). I thought about trying to make
 * a general stackable connection system, but it seemed like overkill -
 * something is wrong if we have 15 filters on top of a socket. Anyway,
 * anything else which wishes to stack can use the same method. The only
 * disadvantage is we have to write wrappers for all the socket methods,
 * even if we only stack over read and write. Thinking about it, the
 * abstraction problem is that there is more in CONNECTION than there
 * needs to be. Ideally it would have only (void*)data and methods. */